Explanation: When abandoning ship, securing the EPIRB (Emergency Position-Indicating Radio Beacon) to the survival craft ensures it remains with the survivors. The EPIRB transmits a distress signal on 406 MHz to satellites, which relays vessel ID and position, and a 121.5 MHz homing signal. Keeping it secured guarantees its signal accurately indicates the craft's location. The SART (Search and Rescue Transponder) operates by responding to X-band radar from search vessels or aircraft. To maximize its effective detection range, it must be mounted as high as possible. This elevation extends the radar horizon, making it detectable from greater distances by SAR assets. Option A is incorrect as portable Inmarsat units are not standard equipment on all survival craft. Option B is incorrect because EPIRBs are pre-programmed with vessel information, and SARTs do not transmit their own location proactively; they respond to incoming radar pulses. Option C is incorrect because SARTs generally require manual deployment and elevation, and do not automatically float free and operate.